Tencent

Tencent/MMKV

An efficient, small mobile key-value storage framework developed by WeChat. Works on Android, iOS, macOS, Windows, POSIX, and OHOS.

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README.md

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中文版本请参看[这里](./README_CN.md)

MMKV is an **efficient**, **small**, **easy-to-use** mobile key-value storage framework used in the WeChat application. It's currently available on **Android**, **iOS/macOS**, **Windows**, **POSIX** and **HarmonyOS NEXT**, with experimental **Kotlin Multiplatform** support.

# MMKV for Kotlin Multiplatform

The v2.4.2 Kotlin Multiplatform package is experimental and currently targets
Android and iOS. Its API and artifact layout may change in a future release.
Add it to the shared module:

```kotlin
kotlin {
    sourceSets {
        commonMain.dependencies {
            implementation("com.tencent:mmkv-kmp:2.4.2")
        }
    }
}
```

Supported targets are Android, `iosArm64`, `iosSimulatorArm64`, and `iosX64`. See the [Kotlin Multiplatform guide](./KMP/README.md) for initialization and packaging details.

# MMKV for Android

## Features

* **Efficient**. MMKV uses mmap to keep memory synced with files, and protobuf to encode/decode values, making the most of Android to achieve the best performance.
  * **Multi-Process concurrency**: MMKV supports concurrent read-read and read-write access between processes.

* **Easy-to-use**. You can use MMKV as you go. All changes are saved immediately, no `sync`, no `apply` calls needed.

* **Small**.
  * **A handful of files**: MMKV contains process locks, encode/decode helpers and mmap logics, and nothing more. It's really tidy.
  * **About 50K in binary size**: MMKV adds about 50K per architecture on App size, and much less when zipped (APK).

## Getting Started

### Installation Via Maven
Add the following lines to `build.gradle` on your app module:

```gradle
dependencies {
    implementation 'com.tencent:mmkv:2.4.2'
    // replace "2.4.2" with any available version
}
```

Starting from v2.0.0, MMKV **no longer supports 32-bit** arch and API level 22 or 21, if you want 32-bit or API level 21~22, use v1.3.x LTS series.

For other installation options, see [Android Setup](https://github.com/Tencent/MMKV/wiki/android_setup).

### Quick Tutorial
You can use MMKV as you go. All changes are saved immediately, no `sync`, no `apply` calls needed.  
Setup MMKV on App startup, say your `Application` class, add these lines:

```Java
public void onCreate() {
    super.onCreate();

String rootDir = MMKV.initialize(this);
    System.out.println("mmkv root: " + rootDir);
    //……
}
```

MMKV has a global instance, that can be used directly:

```Java
import com.tencent.mmkv.MMKV;
    
MMKV kv = MMKV.defaultMMKV();

kv.encode("bool", true);
boolean bValue = kv.decodeBool("bool");

kv.encode("int", Integer.MIN_VALUE);
int iValue = kv.decodeInt("int");

kv.encode("string", "Hello from mmkv");
String str = kv.decodeString("string");
```

MMKV also supports **Multi-Process Access**. Full tutorials can be found here [Android Tutorial](https://github.com/Tencent/MMKV/wiki/android_tutorial).

## Performance
Writing random `int` for 1000 times, we get this chart:  
![](https://github.com/Tencent/MMKV/wiki/assets/profile_android_mini.png)  
For more benchmark data, please refer to [our benchmark](https://github.com/Tencent/MMKV/wiki/android_benchmark).

# MMKV for iOS/macOS

## Features

* **Efficient**. MMKV uses mmap to keep memory synced with files, and protobuf to encode/decode values, making the most of iOS/macOS to achieve the best performance.
 
* **Easy-to-use**. You can use MMKV as you go, no configurations are needed. All changes are saved immediately, no `synchronize` calls are needed.

* **Small**.
  * **A handful of files**: MMKV contains encode/decode helpers and mmap logics and nothing more. It's really tidy.
  * **Less than 30K in binary size**: MMKV adds less than 30K per architecture on App size, and much less when zipped (IPA).

## Getting Started

### Installation Via CocoaPods:
  1. Install [CocoaPods](https://guides.CocoaPods.org/using/getting-started.html);
  2. Open the terminal, `cd` to your project directory, run `pod repo update` to make CocoaPods aware of the latest available MMKV versions;
  3. Edit your Podfile, add `pod 'MMKV'` to your app target;
  4. Run `pod install`;
  5. Open the `.xcworkspace` file generated by CocoaPods;
  6. Add `#import <MMKV/MMKV.h>` to your source file and we are done.

For other installation options, see [iOS/macOS Setup](https://github.com/Tencent/MMKV/wiki/iOS_setup).

### Quick Tutorial
You can use MMKV as you go, no configurations are needed. All changes are saved immediately, no `synchronize` calls are needed.
Setup MMKV on App startup, in your `-[MyApp application: didFinishLaunchingWithOptions:]`, add these lines:

```objective-c
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // init MMKV in the main thread
    [MMKV initializeMMKV:nil];

//...
    return YES;
}
```

MMKV has a global instance, that can be used directly:

```objective-c
MMKV *mmkv = [MMKV defaultMMKV];
    
[mmkv setBool:YES forKey:@"bool"];
BOOL bValue = [mmkv getBoolForKey:@"bool"];
    
[mmkv setInt32:-1024 forKey:@"int32"];
int32_t iValue = [mmkv getInt32ForKey:@"int32"];
    
[mmkv setString:@"hello, mmkv" forKey:@"string"];
NSString *str = [mmkv getStringForKey:@"string"];
```

MMKV also supports **Multi-Process Access**. Full tutorials can be found [here](https://github.com/Tencent/MMKV/wiki/iOS_tutorial).

## Performance
Writing random `int` for 10000 times, we get this chart:  
![](https://github.com/Tencent/MMKV/wiki/assets/profile_mini.png)  
For more benchmark data, please refer to [our benchmark](https://github.com/Tencent/MMKV/wiki/iOS_benchmark).

# MMKV for Windows

## Features

* **Efficient**. MMKV uses mmap to keep memory synced with files, and protobuf to encode/decode values, making the most of Windows to achieve the best performance.
  * **Multi-Process concurrency**: MMKV supports concurrent read-read and read-write access between processes.

* **Easy-to-use**. You can use MMKV as you go. All changes are saved immediately, no `save`, no `sync` calls are needed.

* **Small**.
  * **A handful of files**: MMKV contains process locks, encode/decode helpers and mmap logics, and nothing more. It's really tidy.
  * **About 10K in binary size**: MMKV adds about 10K on application size, and much less when zipped.

## Getting Started

### Installation Via Source
1. Getting source code from git repository:
  
   ```
   git clone https://github.com/Tencent/MMKV.git
   ```
  
2. Add `Core/core.vcxproj` to your solution;
3. Add `MMKV` project to your project's dependencies;
4. Add `$(OutDir)include` to your project's `C/C++` -> `General` -> `Additional Include Directories`;
5. Add `$(OutDir)` to your project's `Linker` -> `General` -> `Additional Library Directories`;
6. Add `mmkv.lib` to your project's `Linker` -> `Input` -> `Additional Dependencies`;
7. Add `#include <MMKV/MMKV.h>` to your source file and we are done.

note:

1. MMKV is compiled with `MT/MTd` runtime by default. If your project uses `MD/MDd`, you should change MMKV's setting to match your project's (`C/C++` -> `Code Generation` -> `Runtime Library`), or vice versa.
2. MMKV is developed with Visual Studio 2017, change the `Platform Toolset` if you use a different version of Visual Studio.

For other installation options, see [Windows Setup](https://github.com/Tencent/MMKV/wiki/windows_setup).

### Quick Tutorial
You can use MMKV as you go. All changes are saved immediately, no `sync`, no `save` calls needed.  
Setup MMKV on App startup, say in your `main()`, add these lines:

```C++
#include <MMKV/MMKV.h>

int main() {
    std::wstring rootDir = getYourAppDocumentDir();
    MMKV::initializeMMKV(rootDir);
    //...
}
```

MMKV has a global instance, that can be used directly:

```C++
auto mmkv = MMKV::defaultMMKV();

mmkv->set(true, "bool");
std::cout << "bool = " << mmkv->getBool("bool") << std::endl;

mmkv->set(1024, "int32");
std::cout << "int32 = " << mmkv->getInt32("int32") << std::endl;

mmkv->set("Hello, MMKV for Windows", "string");
std::string result;
mmkv->getString("string", result);
std::cout << "string = " << result << std::endl;
```

MMKV also supports **Multi-Process Access**. Full tutorials can be found here [Windows Tutorial](https://github.com/Tencent/MMKV/wiki/windows_tutorial).

# MMKV for POSIX

## Features

* **Efficient**. MMKV uses mmap to keep memory synced with files, and protobuf to encode/decode values, making the most of POSIX to achieve the best performance.
  * **Multi-Process concurrency**: MMKV supports concurrent read-read and read-write access between processes.

* **Easy-to-use**. You can use MMKV as you go. All changes are saved immediately, no `save`, no `sync` calls are needed.

* **Small**.
  * **A handful of files**: MMKV contains process locks, encode/decode helpers and mmap logics, and nothing more. It's really tidy.
  * **About 7K in binary size**: MMKV adds about 7K on application size, and much less when zipped.

## Getting Started

### Installation Via CMake
1. Getting source code from the git repository:
  
   ```
   git clone https://github.com/Tencent/MMKV.git
   ```
2. Edit your `CMakeLists.txt`, add those lines:

```cmake
    add_subdirectory(mmkv/POSIX/src mmkv)
    target_link_libraries(MyApp
        mmkv)
    ```
3. Add `#include "MMKV.h"` to your source file and we are done.

For other installation options, see [POSIX Setup](https://github.com/Tencent/MMKV/wiki/posix_setup).

### Quick Tutorial
You can use MMKV as you go. All changes are saved immediately, no `sync`, no `save` calls needed.  
Setup MMKV on App startup, say in your `main()`, add these lines:

```C++
#include "MMKV.h"

int main() {
    std::string rootDir = getYourAppDocumentDir();
    MMKV::initializeMMKV(rootDir);
    //...
}
```

MMKV has a global instance, that can be used directly:

```C++
auto mmkv = MMKV::defaultMMKV();

mmkv->set(true, "bool");
std::cout << "bool = " << mmkv->getBool("bool") << std::endl;

mmkv->set(1024, "int32");
std::cout << "int32 = " << mmkv->getInt32("int32") << std::endl;

mmkv->set("Hello, MMKV for Windows", "string");
std::string result;
mmkv->getString("string", result);
std::cout << "string = " << result << std::endl;
```

MMKV also supports **Multi-Process Access**. Full tutorials can be found here [POSIX Tutorial](https://github.com/Tencent/MMKV/wiki/posix_tutorial).

# MMKV for HarmonyOS NEXT

## Features

* **Efficient**. MMKV uses mmap to keep memory synced with file, and protobuf to encode/decode values, making the most of native platform to achieve best performance.
  * **Multi-Process concurrency**: MMKV supports concurrent read-read and read-write access between processes.

* **Easy-to-use**. You can use MMKV as you go. All changes are saved immediately, no `sync`, no `flush` calls needed.

* **Small**.
  * **A handful of files**: MMKV contains process locks, encode/decode helpers and mmap logics and nothing more. It's really tidy.
  * **About 600K in binary size**: MMKV adds about 600K per architecture on App size, and much less when zipped (HAR/HAP).

## Getting Started
### Installation via OHPM:

```bash
ohpm install @tencent/mmkv
```
### Quick Tutorial
You can use MMKV as you go. All changes are saved immediately, no `sync`, no `apply` calls needed.  
Setup MMKV on App startup, say your `EntryAbility.onCreate()` function, add these lines:

```js
import { MMKV } from '@tencent/mmkv';

export default class EntryAbility extends UIAbility {
  onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {
    let appCtx = this.context.getApplicationContext();
    let mmkvRootDir = MMKV.initialize(appCtx);
    console.info('mmkv rootDir: ', mmkvRootDir);
    ……
  }
```

MMKV has a global instance, that can be used directly:

```js
import { MMKV } from '@tencent/mmkv';
    
let mmkv = MMKV.defaultMMKV();
mmkv.encodeBool('bool', true);
console.info('bool = ', mmkv.decodeBool('bool'));
    
mmkv.encodeInt32('int32', Math.pow(2, 31) - 1);
console.info('max int32 = ', mmkv.decodeInt32('int32'));
    
mmkv.encodeInt64('int', BigInt(2**63) - BigInt(1));
console.info('max int64 = ', mmkv.decodeInt64('int'));
    
let str: string = 'Hello OpenHarmony from MMKV';
mmkv.encodeString('string', str);
console.info('string = ', mmkv.decodeString('string'));

let arrayBuffer: ArrayBuffer = StringToArrayBuffer('Hello OpenHarmony from MMKV with bytes');
mmkv.encodeBytes('bytes', arrayBuffer);
let bytes = mmkv.decodeBytes('bytes');
console.info('bytes = ', ArrayBufferToString(bytes));
```

As you can see, MMKV is quite easy to use.
For the full documentation, see [HarmonyOS NEXT Tutorial](https://github.com/Tencent/MMKV/wiki/ohos_setup).

## License
MMKV is published under the BSD 3-Clause license. For details check out the [LICENSE.TXT](./LICENSE.TXT).

## Change Log
Check out the [CHANGELOG.md](./CHANGELOG.md) for details of change history.

## Contributing

If you are interested in contributing, check out the [CONTRIBUTING.md](./CONTRIBUTING.md), also join our [Tencent OpenSource Plan](https://opensource.tencent.com/contribution). MMKV has officially joined the [Tencent Device-oriented Service Product Alliance](https://tds-union.qq.com/), working together with other alliance members to build an open and mutually beneficial frontend technology product ecosystem.

To give clarity of what is expected of our members, MMKV has adopted the code of conduct defined by the Contributor Covenant, which is widely used. And we think it articulates our values well. For more, check out the [Code of Conduct](./CODE_OF_CONDUCT.md).

## FAQ & Feedback
Check out the [FAQ](https://github.com/Tencent/MMKV/wiki/FAQ) first. Should there be any questions, don't hesitate to create [issues](https://github.com/Tencent/MMKV/issues).

## Personal Information Protection Rules
User privacy is taken very seriously: MMKV does not obtain, collect or upload any personal information. Please refer to the [MMKV SDK Personal Information Protection Rules](https://support.weixin.qq.com/cgi-bin/mmsupportacctnodeweb-bin/pages/aY5BAtRiO1BpoHxo) for details.

Repository info

Default branch: master
Latest version: v2.4.2
Created: 2018-09-17
Last activity: 2026-10-08
License: Other
Open issues: 1
Watchers: 289

Topics

android flutter golang ios key-value kotlin macos ohos python swift tvos visionos watchos wechat windows

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